Date: Wed, 26 Mar 1997 21:13:58 -0700 From: vanmaren@fast.cs.utah.edu (Kevin Van Maren) To: schluntz@pinpt.com, smp@csn.net Cc: freebsd-smp@freefall.freebsd.org Subject: Re: SMP and 3/486's Message-ID: <199703270413.VAA07660@fast.cs.utah.edu>
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> Hi, > > Does the SMP kernal in FreeBSD support systems with multiple 386's or 486's? > > I see a lot of talk about P5's and P6's but I have known about multi-processor > > systems using intel chips for a number of years, using 386's and 486's. > > no, 386/486 chips just can't do this sort of thing *efficiently*, > the P5/P6 were designed to do SMP. I'm not saying it couldn't be > done, just that it doesn't appear worth the effort to those involved... > Some of the first (then) large-scale multiprocessors were 386 based. Also, the APIC was designed for the i486, so it does work well. (Unfortunatly, it has been discontinued). I have access to a dual 486 made by VTECH -- apparently it runs Windows NT rather well. I won't argue that a dual 486 will do better, or even as well as, a dual Pentium, but it will do much better than a single 486. I have probe code for the dual 486 (not SMP compliant), but the startup code is a little more complicated for discrete APICs. The other problem is that (in this case), the three APICs are at different addresses (rather than just the two), and they share the same physical page. If you tell what processor you are on by using the APIC ID, then this won't work :( (I've just been too busy lately to play with it, or even FreeBSD on the dual Pro/200). Kevin
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